Hydraulic transport device and electrohydraulic control module

ABSTRACT

A hydraulic transport device for transporting a hydraulic medium. The device includes at least one externally toothed gear pump that is driven by an electric motor, and a control device attached to the pump. A passive rotational speed detection element is arranged in the pump and interacts with an active rotational speed detection element that is arranged in the control device to detect the rotational speed of the pump shaft.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of International Application Ser. No.PCT/DE2011/000405, having an international filing date of 14 Apr. 2011,and designating the United States, the entire contents of which arehereby incorporated by reference to the same extent as if fullyrewritten.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic transport device fortransporting a hydraulic medium including at least one pump driven by anelectric motor, and a control device. The invention also relates to anelectrohydraulic control module with such a hydraulic transport device.

2. Description of the Related Art

Such transport devices are needed for hydraulic controls of vehicletransmissions, among other things. The pumps generate a volumetric flowfor different tasks in the hydraulic control, such as actuatingadjusting cylinders that require a high pressure and/or volumetric flow,or supplying coolant and/or lubricating medium to specific components.In some of these hydraulic controls, the pumps are driven by means of anelectric motor.

To ensure that the hydraulic control functions optimally, control of thespeed of the pump and/or the electric motor driving the pump isfrequently required; consequently, it is necessary to detect the speed.It is known to detect the pump speed directly as the speed of theelectric motor, that is, to sense the speed directly on or in theelectric motor that drives the pump. The detected speed signals may beprocessed and sent via a signal line and plug-in connections to acontrol device where they are processed further. The signal lines canalso serve as control or power supply lines.

The disadvantage of that type of speed sensing is that additionalinstallation space is required for the electric motor, which can causesubstantial problems depending on the installation space requirements.Another disadvantage is that a device for detecting speed that ismounted on the electric motor requires additional housing parts andhence additional costs. The same holds true for transmitting the signaland contacting the line between the electric motor and the controldevice.

A method is known from German patent application DE 100 06 320 A1 forelectrically connecting an electric motor and electronic moduleincluding at least one speed sensor that can be positioned on a supportbody to detect the speed of the electric motor.

An object of the present invention is to provide an economical hydraulictransport device requiring little installation space.

SUMMARY OF THE INVENTION

The object is achieved by a hydraulic transport device for transportinga hydraulic medium including at least one pump that is driven by anelectric motor and a control device. A passive detection element,especially a speed detection element, is arranged in the pump, whichthen interacts with an active detection element, especially a speeddetection element, that is arranged in the control device. According toanother aspect of the invention, the active speed detection element isintegrated in the control device. That has the advantage that thetransmission of the speed signal by a signal line between the electricmotor and control device can be completely discarded. Furthermore, noadditional housing parts are required for the speed sensors.Alternatively, or in addition to the speed detection elements, otherdetection elements can be used, such as torque detection elements. Theelectric motor is preferably a BLDG (brushless direct current) electricmotor that is provided with detection elements, especially sensors.

A preferred exemplary embodiment of the hydraulic transport device ischaracterized in that the pump is arranged between the electric motorand the control device. The pump is preferably designed as a gear pump,especially as an externally toothed gear pump.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the pump includes a pump shaft with an end towhich the passive speed detection element is attached. The other end ofthe pump shaft can, for example, be coupled to the electric motor bymeans of a coupling.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the passive speed detection element includes amagnet that is non-rotatably connected to the pump shaft. The magnetinteracts electromagnetically with the active speed detection elements.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the pump shaft is arranged coaxially to a motorshaft of the electric motor. The pump shaft and the motor shaftpreferably have a common axis of rotation.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the active speed detection element is arrangedin a control housing body. The control housing body is part of a housingof the control device.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the control housing body includes a relativelythin housing wall that is arranged between the active and the passivespeed detection element. When the pump is operating, the speed signalsare transmitted through the housing wall. The transmitted speed signalscan be directly processed further in the control device.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the pump is arranged in a control platearrangement that is positioned between the control housing body and theelectric motor. A plurality of pumps can also be arranged in the controlplate arrangement. A plurality of control plates are preferably arrangedbetween the control housing body and the electric motor. A pump ispreferably arranged in each control plate. It is particularly preferablefor two control plates with one pump each to be arranged between thecontrol housing body and the electric motor.

Another preferred exemplary embodiment of the hydraulic transport deviceis characterized in that the electric motor is mounted on the controlplate arrangement. The electric motor is, for example, screwed onto thecontrol plate arrangement.

Another preferred embodiment of the hydraulic transport device ischaracterized in that at least one tooth of a pump gear is the passivedetection element. The advantage of sensing, especially speed sensing,using the teeth of the pump gear is that no additional passive detectionelement is required.

The present invention also relates to an electrohydraulic control modulewith the above-described hydraulic transport device. Theelectrohydraulic control module preferably serves to control a vehicletransmission. The hydraulic transport device serves to generate ahydraulic volumetric flow for various tasks in the hydraulic control ofthe vehicle transmission. The functioning of the hydraulic control canbe optimized by sensing rotational speed with the speed sensing elementsarranged according to the invention.

BRIEF DESCRIPTION OF THE DRAWING

Additional advantages, features, and details of the invention aredescribed in the following description in which an exemplary embodimentis described in detail with reference to the drawing. Shown in thedrawing are:

FIG. 1 shows a cross section of an embodiment of an electrohydrauliccontrol module with an embodiment of a hydraulic transport deviceaccording to the invention, and

FIG. 2 shows a cross section of an embodiment of a pump of the hydraulictransport device shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a cross section of an electrohydraulic control module 1with a hydraulic transport device 4 according to an exemplary embodimentof the invention. The hydraulic transport device 4 includes a first pump6 and a second pump 8. The two pumps 6, 8 are driven by an electricmotor 10. The electric motor 10 is connected via an electric connectingcable 11, 12 to an electric power supply.

The control module 1, or the transport device 4, also includes a controldevice 15 with a control housing body 16. A control plate arrangement 20including a first control plate 21 and a second control plate 22 isarranged between the control housing body 16 and the electric motor 10.An intermediate plate 23 is arranged between the two control plates 21,22. Screws 25 are used to fasten the electric motor 10 to the topcontrol plate 21, as shown in FIG. 1, of the control plate arrangement20.

The first pump 6 is integrated in the first control plate 21. The secondpump 8 is integrated in the second control plate 22. The two pumps 6, 8are both designed as externally toothed gear pumps and are driven by amotor shaft 28 of the electric motor 10. The free end of the motor shaft28 is coupled by means of a coupling 29 to a common pump shaft 30 of thetwo pumps 6, 8.

The coupling 29 non-rotatably connects the free end of the motor shaft28 to a top end of the pump shaft 30, as shown in FIG. 1. The motorshaft 28 and the pump shaft 30 have a common rotational axis 33 thatextends in the vertical direction in FIG. 1. A bottom end of the commonpump shaft 30, as shown in FIG. 1, can be coupled by means of anothercoupling 34 to a pump gear 35 of the second pump 8. A pump gear of thefirst pump 6 is permanently non-rotatably connected to the common pumpshaft 30.

The second pump 8 includes a pump cover 38 that seals the second controlplate 22 open at the bottom in FIG. 1. Below the coupling 34 of thesecond pump 8, the pump cover 38 includes a recess in which a passive,freely rotatable speed detection element 41 is arranged. The passivespeed detection element 41 is non-rotatably connected to the bottom endof the common pump shaft 30, as shown in FIG. 1.

The passive speed detection element 41 is preferably designed as amagnet and is fixedly connected to the bottom end of the common pumpshaft 30, as shown in FIG. 1. The passive speed detection element 41interacts electromagnetically with an active speed element 42 that isindicated in FIG. 1 by a rectangle. The active speed detection element42 is separated from the passive speed detection element 41 by arelatively thin housing wall of the control housing body 16 and byanother relatively thin housing wall of the pump cover 38.

The two housing walls are designed to be thin enough for the speedsignals to be transmitted from the passive speed detection element 41 tothe active speed detection element 42 while the hydraulic transportdevice 4 is operating. The two speed detection elements 41, 42 togetherconstitute a speed sensor device 40 with which the rotational speed ofthe common pump shaft 30, and hence the rotational speed of the motorshaft 28 of the electric motor 10, can be easily detected. The detectedspeed signals can be directly processed further in the control device15.

FIG. 2 shows that the pump gear 35 for the second pump 8 is designed asan external gear with external teeth 54. The pump gear 35 meshes withanother externally toothed gear 55 to transport hydraulic medium as anexternally toothed gear pump. By using a correspondingly suitable activespeed detection element, the rotational speed of the common pump shaft30 can also be sensed by means of the teeth of the pump gears 35, 55. Inthis case, the passive speed detection element is constituted by atleast one tooth, or all of the teeth, of at least one external gear ofthe externally toothed gear pump 8. An additional external passivesensor detection element can then be eliminated.

1. A hydraulic transport device for transporting a hydraulic medium,said device comprising: at least one rotary hydraulic pump having a pumphousing and that is driven by an electric motor; a control deviceconnected with the pump housing and including a control device housing;a passive rotational speed detection element arranged within the pumphousing; and an active rotational speed detection element arrangedwithin the control device for interaction with the passive rotationalspeed detection element for detecting a rotational speed of thehydraulic pump.
 2. The hydraulic transport device according to claim 1,wherein the pump is arranged between the electric motor and the controldevice.
 3. The hydraulic transport device according to claim 1, whereinthe pump includes a pump shaft having an end that is attached to thepassive rotational speed detection element.
 4. The hydraulic transportdevice according to claim 3, wherein the passive rotational speeddetection element includes a magnet that is non-rotatably connected tothe pump shaft.
 5. The hydraulic transport device according to claim 3,wherein the pump shaft is coaxial with a motor shaft of the electricmotor.
 6. The hydraulic transport device according to claim 1, whereinthe active rotational speed detection element is arranged in the controldevice housing.
 7. The hydraulic transport device according to claim 6,wherein the control device housing includes a housing wall that isarranged between the active and the passive rotational speed detectionelements.
 8. The hydraulic transport device according to claim 6 whereinthe pump is arranged against a control plate that is positioned betweenthe control device housing and the electric motor.
 9. The hydraulictransport device according to claim 8, wherein the electric motor ismounted on the control plate.
 10. The hydraulic transport deviceaccording to claim 1, wherein at least one tooth of a pump gear having aplurality of teeth is the passive rotational speed detection element.11. The hydraulic transport device according to claim 7, wherein thecontrol device housing wall has a thickness that allows the passagetherethrough of magnetic flux between the active and passive rotationalspeed elements.